Field of Invention
The present invention relates to a flame retardant in the field of chemical materials, wherein a DOPO derivative compound is reacted with a epoxy group of a epoxy resin under the presence of a curing agent so as to obtain a cured non-halogen flame-retardant epoxy composite being friendly to the environment and characterized of low dielectric property and excellent heat resistance.
Description of Related Art
As defined by the chemical structure of itself, the epoxy resin has great performances in terms of reactivity, toughness, flexibility and the like, and also has good mechanical and electrical performances as well as dimensional stability; the adhesion of the epoxy resin to different substrates is also great. The cured epoxy resin can not only keep the original properties of the substrates, but also have improved barrier properties to water, gas and chemicals, as well as having advantages of light weight and low cost. Therefore the epoxy can be widely applied in electronics and aerospace industries, especially in the fields of semiconductor packaging materials and substrates of printed circuit boards. On the other hand, with the rapid changes in science and technology, many computer information industries, communication industries and consumer electronics also vary quickly. Throughout the whole electronics industry, its development features are as follows:
1. the using frequency becomes higher; and
2. the manufacturing technical level becomes higher.
For example, the printed circuit board are developed in the tendency of low-dielectric, low thermal expansion, multilayer, high heat resistance and the like. Meanwhile, for satisfying the requirement of being friendly to the environment, the electronics and communication products are also developed in the tendency of being lightweight, thin, short and small, having high reliability, multiple functions and being environment friendly. With high frequency of the use of wireless networks and communication devices, the high-frequency substrate will become the future development trend. The requirements for materials used in the high-frequency substrate are no more than being capable of transferring data quickly, without causing data loss or data interference during the transfer process. Therefore the material selected for manufacturing the high-frequency communication device should have the following basic characteristics:
(1) low and stable dielectric constant;
(2) small dielectric consumption factor;
(3) low water absorption;
(4) excellent chemical resistance;
(5) great heat resistance; and
(6) being non-halogen and flame-retardant.
Relatively, an organic phosphorus flame retardant is generally recognized as an important specie for replacing the halogen flame retardant, since the organic phosphorus flame retardant has low smoke amount, is not liable to form a poisonous gas and a corrosive gas, and is environment friendly. In the field of epoxy resin and board′ material, the application of reactive-type organic phosphorus flame retardant, such as a DOPO derivative, is common, where such a flame retardant is linked onto the epoxy resin through covalent bonding, which has smaller influence to the material property. The application of an additive-type organic phosphorus flame retardant in the epoxy resin field is relative less, since the epoxy resin field has high requirements for the melting point and suability of flame retardant, which are difficult to reach for general flame retardants.
There are few patent reports for DOPO derivatives linked through ether bonding as an additive-type flame retardant (see, Japanese Patent Laid-Open No. Heisei 11[1999]-106619 and Japanese Patent Laid-Open No. P2001-270993A). However, studies on synthesis methods of the additive-type flame retardant are less and such a preparation method has low yield and high cost. There is no report of applying it as a flame retardant of an epoxy composite on a high-frequency substrate.